Colorectal cancer has a slow onset and various clinical manifestations, so it is very easy to be misdiagnosed and missed. It often fails to achieve the expected treatment effect due to misdiagnosis and misdiagnosis, and even delays the disease and loses the opportunity of surgical cure, and brings heavy economic burden to patients and aggravates their pain. The reasons are as follows: 1. Different tumor sites and different symptoms The sites can be rectum, sigmoid colon, descending colon, splenic flexure of colon, ascending colon, hepatic flexure of colon, transverse colon, different pathological typing, different Dukes’ stage, and often similar to the symptoms of benign diseases in the corresponding sites, so they are often misdiagnosed. 2. Insufficient detailed medical history, especially the lack of understanding of blood stool Detailed examination of the cause of blood stool is the key to finding diagnostic clues, colorectal cancer is mostly seen in pus and blood stool, mixed with feces and blood or visible fecal pressure, which is related to the location of cancer tumors, so for older people, especially those with abdominal pain and abdominal lumps, be alert to the possibility of colorectal cancer, do not just superficially think it is “hemorrhoids Therefore, for those who are older, especially with abdominal pain and abdominal lumps, they should be alerted to the possibility of colorectal cancer and not just superficially think that it is “hemorrhoids”. Rectal finger diagnosis is even more crucial. 3.Insufficient understanding of the pathogenesis of certain intestinal infectious diseases The onset of colorectal cancer is not seasonal, and most of them are middle-aged and elderly patients, with more bloody stools than purulent stools, bacterial culture is often negative, and the treatment effect is poor according to bacillary dysentery, which can be distinguished from “bacillary dysentery”. 4.Patients with anemia as the first symptom are misdiagnosed as “iron deficiency anemia” and are often misdiagnosed as “iron deficiency anemia” and treated with iron supplementation. Therefore, in patients with unexplained anemia, the presence of occult gastrointestinal bleeding should be considered. Sequential fecal occult blood test is an important tool to screen for occult gastrointestinal bleeding. Doctors are not vigilant about rectal cancer Doctors are not vigilant about rectal cancer and are blinded by the complications or superficial phenomena of the patients without further analysis of the condition. For example, misdiagnosis as “dysentery”, improvement or even complete remission within a short period of time after treatment with pitocin, ignoring the fact that rectal cancer is combined with infection and the application of antibiotic treatment may also improve the symptoms; misdiagnosis as “intestinal polyp”, analysis may be the patient after polypectomy The patient may have relaxed vigilance after polypectomy and failed to review regularly, resulting in recurrence of polyps and malignant changes. Given that the early symptoms of rectal cancer are not obvious, even if there are symptoms, they are not specific, similar to hemorrhoids and enteritis, so it is very easy to misdiagnose. Rectal examination is the key to reduce misdiagnosis. If the rectal examination is suspicious, walking proctoscopy and sigmoidoscopy should be performed to directly see the shape and size of the lesion and biopsy, therefore, for those who visit us with anorectal symptoms, rectal examination and anoscopy should be done carefully. For patients aged >40 years, sigmoidoscopy should be routinely performed, which may detect precancerous lesions or early cancer.